It is now well established in both the experimental animal and man that M-mode echocardiography can record areas of regional asynergy in acute and chronic myocardial ischemia. Unfortunately because of the limited area of the ventricle examined by the M-mode beam, it has not been possible to quantitatively determine the extent of abnormal wall motion or its relationship to corresponding areas of infarct or ischemia. Cross-sectional echocardiography, by increasing our field vision and providing correct spatial orientation, should permit quantitation of extent of abnormal wall motion. We propose that the area of abnormal wall motion observed following acute myocardial infarction should bear a direct relationship to the histologic area of infarction or ischemia. To examine this hypothesis we plan, 1) to determine the ability of cross-sectional echocardiography to quantitate areas of abnormal wall motion following acute myocardial infarction in the experimental animal, 2) to determine the relationship of wall motion abnormalities to regional myocardial perfusion using radio labeled microspheres, 3) to determine the relationship of areas of abnormal wall motion to histologically determined infarct size, and 4) to examine the relationship of initial wall motion changes to the eventual area of established infarct.